Electrical outlet safety accessory



Oct. 3, 1950 B. B. BIERCE 2,524,250

ELECTRICAL OUTLET SAFETY ACCESSORY Filed Aug. 3, 1946 l 2 Sheets-'Sheet 2 .ngi L 3% ffm@ Patented ct. 3, 19570 UNITED ELECTRICAL OUTLET SAFETY ACCESSORY Burton B. Bierce, Pewaukee, Wis., assigner of one-half to Elwin A. Andi-us, Milwaukee, Wis.

Application August 3, 1946, Serial No. 688,324

6 Claims. l This invention relates to standard household electrical outlets and constitutes a safety accessory therefor.

The object of the invention is to provide a device which is easily installed for use in conjunction with the regular household type outlet which will render the outlet safe from the meddling of children and of possible injury to children and others by shocks.

`Another object of the invention is to provide a device easily installed and used in conjunction with the regular household type outlet which provides a ground connection suitable for grounding electrical apparatus connected thereto and which is safe against accidental shorting.

Another object is to provide an accessory which will automatically prevent dirt and moisture from entering the slots for the connecting prongs.

Another object is to provide an accessory having a rotary cover plate which automatically covers the Contact slots when the prongs of a plug are removed from the slots.

Another object is to provide such an accessory into which the prongs of the plug are initially inserted in the same relative position at the start of the plugging operation as at the final position of the plugging operation.

Another object is to provide such an accessory which is adaptable to any standard household electrical outlet and which is not unduly large or unsightly, which may readily be artistically designed, and may be manufactured at low cost.

Another object is to provide such an accessory which will fit over the regular electrical outlet, and is easily secured and connected thereto with a single adjustment.

Other objects and advantages will appear in the following description of an embodiment of the invention illustrated in the accompanying draw ings.

In the drawings:

Figure l is a perspective View of the accessory as adapted to a standard double outlet showing one of the mechanisms exploded to show the parts thereof prior' to assembly;

Fig. 2 is a section through the accessory asm sembled with an outlet and taken on. the longitudinal center line of the structure;

Fig. 3 is a section taken transversely ci Fig. 2 across the unit on line 3-3 of Fig. 2 and showing a standard plug inserted therein;

Fig. 4 is a section taken on line 4-4 of Fig. 3;

Fig. 5 is a section taken on line 5--5 oi Fig. 3;

Fig. 6 is a face elevation of the accessory;

Fig. 7 is a rear elevation view of the accessory;

CII

Fig. 8 is a perspective view of a plug having a third central prong for use with the outlet in grounding electrical apparatus; and

Fig. 9 is a view similar to Fig. 3 but showing the plug illustrated in Fig. 8 inserted in the unit.

The outlet shown in the drawings with which the invention is employed is a standard double electrical outlet. The safety accessory of the invention may be constructed for use with a single outlet or with outlets of any multiple.

The plug providing the ground connection to which the invention is particularly adapted constitutes the subject matter of a copending application Serial No. 680,600 filed on July l, 194.6, now abandoned by the present inventor. Standard outlet plugs also may be employed with the sai'ety device of the invention.

The structure of the present invention includes the particular outlet receptacle closure mechanism which constitutes the subject matter of a copending application Serial No. 680,691 iiled on July l, 1946 by the present inventor.

The subject of the present invention is an accessory means whereby any standard electrical outlet may be adapted to use with the above menm tioned plug and provided with the safety features of the above mentioned outlet.

The accessory comprises a base I of phenolic resin, porcelain or a suitable synthetic plastic insulating material, two pairs of electrical contact prongs 2 extending from the rear side of the base I to engage the standard double electrical Wall outlet, and the two receptacle mechanisms 3 y disposed in the front side of the base I.

The base I is rectangular in shape and has a recess 4 on the back side suiciently large to accommodate the body 5 of the standard outlet so that the base l will rest ilush against the wall.

Two pairs of slots E in the base I hold the prongs 2 and register with the slots in the receptacle 5 when the base I is in position.

The prongs 2 are fitted in the corresponding slots to make electrical contact with the prongs 'i ofy the standard plug 8 shown in Fig. 3, and extend rearwardly from the base I to t within and make electrical contact with the conducting elements within the outlet receptacle 5.

The slots open into two circular sockets 9 in the face of the base I. The sockets S contain the mechanisms s which comprise the inner circular discs It and outer circular discs, II which serve to cover slots 6 when in normal position to prevent accidental snorting of the contacts 2.

Each disc lli has a pair of slots i2. and each disc I I has a pair of slots I3, corresponding to.

3 the slots 6 in the base I. Both discs are mounted for rotation in the sockets 9 and are held in place by a central rivet I4 which leaves the same free to turn thereon.

When in normal position, disc IIJ is turned 90 from a position of registry of its slots I2 with the corresponding slots G in the base I, so that the disc completely covers slots 6.

When in normal position, disc II has its slots I3 in alignment with slots 6 of base I.

The discs IB and II are biased to normal position by a coil spring i5 preferably of the tension type lying in a circumferential recess I6 in the disc I and secured at one end to a projection I1 in the recess I and at the other end to a pin IB extending into the recess I6 from disc II.

The projection I is disposed about centrally of recess I6 and the spring i5 lies in one end of the recess dened by the projection and one end wall. The other end of recess I6 receives a stop I9 projecting from the side wall of the socket 9.

A groove is cut along the inner corner edge of disc II to receive a part of stop I9.

The stop I9 limits the relative rotational movement of discs i9 and EI and provides for a 90 separation of slots I2 and I3 under the biasing action of spring I5.

When it is desired to insert the prongs 'I of the plug 8 into slots t to make contact with contacts 2, the ends of the prongs I are iirst entered in slots I3v into engagement with disc I0. The plug 8 and disc I i are then turned to the right 90 until the prongs 'e register with and enter slots I2 of disc IS. The plug 8 and discs I0 and II are then turned to the left 90 to the original l plane oi the prongs, and the latter are then pushed into slots G to complete the electrical connection.

The dual disc construction requiring turning in both directions in order to complete the connection provides a protection against the meddling of children which is not present with single discs. it provides an indication of the plane for the prongs of the plug, the outer slots I3 being preferably in alignment with slots 6.

The dual disc construction wherein the discs are biased relative to each other by spring I5 provides for a gripping of the prongs 'I when the connection is completed and thereby prevents accidental displacement of the plug and removal of the prongs. The contacts .a are relieved of any stress from spring I5 since discs i0 and II are iioating with respect to the base I.

When it is desired to remove the plug 8 it is merely pulled straight out, allowing spring I5 to to prongs l of plug E and their manner of insertion in the unit is identical to that of prongs 1 and plug 8 as described above.

The ground connection with the plug is provided by the cylindrical recess 2I in the front end of rivet I which receives the ground prong 22 of l the plug 8'. The cable 23 connecting the plug B with the electrical apparatus to be operated is preferably of the three wire type, one of the wires constituting a ground wire connected to the casing of the apparatus and to central prong 22.

The recess 2| and prong 22 provide simple means for grounding electric motor appliances, electric Shavers and the like and provide greater safety in the operation of all electrical appliances.

A metal strip 24 on the back side of base I connects the two rivets I4 and is connected at its center by screw 25 to the metal bracket 26 supporting the body 5 oi the wall outlet to complete the ground connection when the device is secured in position.

In applying the accessory the base I is first adjusted over the outlet with the prongs 2 entering the slots of the wall outlet until the base I is iiush against the wall and covers the outlet and the body 5 of the outlet fits within the recess 4 on the back side of base I.

The screw 25 is then set in hole 2l in the center of base I and extended into the threaded hole of the bracket 26 and tightened to effect a ground connection between the bracket 2B and the metal strip 24 and firmly secure the base and accessory to the outlet.

The invention may have various embodiments within the scope of the accompanying claims.

I claim:

l. An electrical outlet cover comprising a base having a pair of spaced slots extending therethrough, electrical contacts disposed in said slots, a pair of generally circular discs rotatably mounted on the face of said base, each disc having a pair of slots therethrough corresponding to the slots in said base, means normally biasing one of said discs rotationally relative to the other to a position in which the corresponding slots oi' he discs are out of registry with each other to provide a cover for said contacts, and means interlocking said discs and body rotationally to provide for a normal offsetting of the slots of the inner of the discs relative to the slots in the said base, said base being adapted to removably iit over an electric outlet receptacle with the electric contacts of the base engaging the electrical terminals of the electric outlet.

2. An electric wall outlet accessory cover comprising a body having a generally circular socket with a pair oi spaced slots adapted to register with contact terminals in the outlet, a pair of electrical contact prongs disposed in said slots and adapted to extend from said body into the v-.vall outlet for makingelectrical connection with the outlet terminals, a pair of generally circular discs rotatably mounted in said socket and each having a pair of slots adapted to register with those in said cover body, means normally biasing said discs rotationally relative to each other to a position in which the corresponding slots of the discs are out of registry with each other to provide a cover for said contacts, and means interlocking said discs and body rotationally to provide for a normal oiisetting of the slots in the inner disc relative to the slots in the body and for the normal alignment of the slots in the outer disc with those of the body.

.3. A safety accessory for electrical outlets comprising a cover for said outlet having slots adapted to register with the terminals of said outlet, electrical contacts disposed in said slots and adapted to extend into the outlet to make electrical contact therein, a pair of generally circular discs rotatably mounted in the face of said cover and each disc having a pair of slots therethrough corresponding to the slots in said cover, means normally biasing said discs rotationally relative to each other to a position in which the corresponding slots of the discs are out of registry with each other and the slots of said inner disc are out of registry with the slots of said cover to provide a cover for said contacts, and a ground connection constituting a central pin upon which said discs are rotatably mounted and which has a recess centrally thereof to receive a ground prong of a connecting plug.

4. An electric wall outlet accessory cover comprising a body having a generally circular socket with a pair of spaced slots adapted to register with contact terminals in the outlet, a pair of electrical contact prongs disposed in said slots and adapted to extend from said body into the wall outlet to make electrical connection with the outlet terminals, a pair of generally circular discs rotatably mounted in said socket and each having a pair of slots adapted to register with those in said cover body, means normally biasing said discs rotationally relative to each other to a position in which the corresponding slots of the discs are out of registry with each other to provide a cover for said contacts, means interlocking said discs and body rotationally to provide for a normal offsetting of the slots in the inner disc relative to the slots in the body and for the normal alignment of the slots in the outer disc with those of the body, and a ground connection constituting a central pin upon which said discs are rotatably mounted and which has a recess centrally thereof to receive a ground prong of a connecting plug.

5. An electrical outlet box cover for a double outlet, comprising a base plate adapted to cover the outlet box, a central screw adapted to secure the base to the outlet and to serve as a ground connection from the base to the outlet, a pair of spaced sockets in said base corresponding in position to the outlets and each having a pair of slots corresponding to the terminals of the outlet immediately behind the same, an electric contact member disposed in each slot of the base and adapted to extend into the corresponding outlet to make electrical contact with a corresponding terminal therein, the slots in said base being adapted to receive the corresponding prongs of a plugfor an extension cord, a ground terminal disposed centrally of each socket and adapted to receive a central ground prong of the plug, and a metal strip disposed on the back of said base and connecting said ground terminals with said central screw.

6. An electrical outlet box cover for a double outlet, comprising a base plate adapted to cover the outlet box, a central screw adapted to secure the base to the outlet and to serve as a ground connection from the base to the outlet, a pair of spaced sockets in said base corresponding in position to the outlets and each having a pair of slots corresponding to the terminals of the outlet immediately behind the same, an electric contact member disposed in each slot of the base and adapted to extend into the corresponding outlet to make electrical contact with a corresponding terminal therein, the slots in said base being adapted to receive the corresponding prongs of a plug for an extension cord, a ground terminal disposed centrally of each socket and adapted to receive a central gro-und prong of the plug, a metal strip disposed on the back of said base and connecting said ground terminals with said central screw, a disc in each said socket rotatable on said ground terminal and having a pair of slots corresponding to those in said socket, and a spring normally biasing each corresponding disc to a position where the slots therein are out of registry with those in the corresponding socket to cover said terminals.

BURTON B. BIERCE.

REFERENCES CITED The following references areiof record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,786,292 De Reamer Dec. 23, 1930 1,983,157 Wermine Dec. 4, 1934 1,989,693 Hubbell Feb. 5, 1935 2,119,428 Englar May 31, 1938 2,154,160 Hamilton Apr. 11, 1939 2,299,617 Eisenberg Oct. 20, 1942 FOREIGN PATENTS Number Country Date 684,289 Germany Nov. 25, 1939 496,966 Germany Jan. 19, 1928 475,824 England Nov. 26, 1937 

